Space power systems requirements and issues: the next decade

Some of the more important space power technology issues, requirements, and challenges of the 1990s are described, and the impact of new component technology on the overall performance of space power systems is assessed. Advanced component, subsystem and system technologies that will significantly affect the performance, reliability, and survivability of next-generation baseload and burst mode space power systems are emphasized. Technology disciplines related to power sources (solar/nuclear and chemical), power conversion, energy storage, power conditioning/distribution and control, and waste-heat acquisition, transport, and rejection are primarily addressed. For some of them, performance trends that can be used as the basis for projecting future advanced power-system performance are developed. Performance capabilities for several different types of space power system for both baseload and burst mode applications are postulated on the basis of evolving technology and point designs that incorporate projections of advanced component capabilities     

基于联合仿真的飞机空调系统故障影响

飞机空调系统是飞机的重要组成部分,由于其在飞行过程中环境和工作参数变化较大,易于受到多种因素的影响而成为故障率较高的飞机系统之一。飞机空调系统故障主要发生在飞行过程中,在地面状态难以复现,因此基于联合仿真的飞机空调系统故障影响分析对飞机设计验证和地面维修具有重要意义。首先根据飞机空调系统原理建立了冲压空气进气口模型、发动机压气机模型、压力调节与预冷组件模型、制冷组件模型;然后基于AMESim-Simulink联合仿真平台,模拟飞行过程中空调系统组件性能动态变化过程;最后对典型故障如预冷器泄漏、预冷器空气活门卡死、压力传感器冲击、冲压空气进气作动筒卡死等故障进行模拟,再现了飞行过程中空调系统故障情况,分析了空调组件性能的变化过程。     

A Comparison of Solar-Cell and Battery-Type Power System for Spacecraft

The electrical power systems of orbiting unmanned spacecraft generally consist of energy-conversion devices in combination with energy-storage and conditioning components. The development of efficient pulse-duration modulation regulators suggests configurations smaller, lighter, and cheaper than conventional dissipative voltage regulators. These savings may or may not be realizable, depending upon the system reliability design goal and amount of redundancy required to meet the goal. Three spacecraft electrical power systems, each containing a solar-cell energy converter and using different voltage regulation schemes, are compared for a common mission specification. Each system is made to meet a given reliability goal by a technique that adds redundant components in a manner that minimizes a system design characteristic such as weight. The reliability design goal is kept constant as mission length is increased, permitting system comparison in terms of weight and cost as a function of time.     

Magnetic suspension and balance systems

Conditions necessary for controlled magnetic suspension are reviewed, and various types and configurations of systems are described. The principal components of these systems are discussed. The use of magnetic suspension and balance systems in wind tunnels is then considered, and some aerodynamic results are examined     

Algorithmic, architectural, and beam pattern issues of sidelobecancellation

Various important issues concerning the sidelobe cancellation (SLC) approach for suppressing sidelobe interference signals in radar are investigated. The concepts are presented in a tutorial manner and include: formulating the calculation of the complex weights for the auxiliary channels as an exact least-squares (LS) problem; computing the LS weights using orthogonal transformation for improved numerical accuracy; and mapping orthogonalization-based algorithms onto systolic arrays. The problem of excessive degrees of freedom (EDOF) associated with utilizing too many auxiliary elements when a relatively small number of jammers are present, is also considered. A divisionless orthogonalization-based algorithm is presented for the computation of the auxiliary weights. Many of these issues have previously been either implicitly stated or only individually addressed in various sources by a number of researchers. Besides showing simulation results and the divisionless procedure for obtaining the final auxiliary weights, a major consideration was to present all of the aforementioned concepts in a coherent and unified framework     

军用飞机重叠关键部件二次杀伤易损性的研究

为减缩军用飞机的易损面积,有时会将关键部件的重叠布置作为其方法之一,但在考虑二次杀伤的情况下,重叠布置并不一定会减缩飞机的易损面积,为此分析对比了飞机重叠布置在考虑二次杀伤情况下和不采取重叠布置时易损面积的变化,得出了飞机在重叠布置下易损面积变化的通用计算公式和影响因素。     

Batteries vs. alternatives for storing energy

Electric utilities need quickly-available sources of power for supplying expected and unexpected peak loads. Among useful sources have been the energy stored in water by pumping it to elevated storage reservoirs, in air compressed into underground chambers, and in batteries. A new power source, tBase-load nuclear and coal-fired steam plants generate off-peak energy for recharging the depleted storage facility. The aero-derived gas turbine, challenges the economics of these traditional energy-storage means. These turbines have been designed for aircraft where quick startup, rapid change in output power, and high reliability are essential. With a 1426°C (2600°F) turbine inlet temperature the available efficiencies are 42% in simple-cycle operation and 60% in a combined-cycle power plant. A recent 84-MW natural-gas-burning peak-power plant cost $204 per kW. Pacific Gas and Electric's Helmes River pumped-hydro plant had cost $656 per kW. The combined-cycle gas turbine plants, with their low manpower requirements, are producing power that costs less than power from nuclear power plants. We examine the performance and economics available from these new power sources     

Future trends in space power technology

The status of the US Air Force Space Power Research and Development Program is summarized. Generic issues and requirements affecting the strategic planning of space power advances for the 1990s and beyond are described. The major thrusts of the Air Fore part of the Strategic Defense Initiative Office Space Power Program are highlighted, with emphasis on the ongoing advanced component technology development program. The status of these component technologies in the areas of power sources, energy storage, power management and distribution, and thermal management is described. Technology projections for the full range of envisioned technology options for the foregoing are used as the basis for a series of point designs for deriving the subsystem- and system-level benefits of the technologies. The primary focus is on baseload (CW) power systems operating in the range from 100 W for small satellites to 50 kW for potential large surveillance satellites. The secondary focus is on large, multimegawatt pulsed power systems and related components for potential applications such as directed energy. Potential `trump card' technologies related to energy conversion, storage, power electronics, and thermal management are identified     

High Voltage/High Power for Airborne Applications

The Air Force has requirements for large amounts of electrical power at high voltage (up to hundreds of kilovolts) for certain airborne applications. Because of the severe weight and volume constraints, these systems cannot be realized using conventional technology. The Air Force, therefore, has been heavily involved in the development of lightweight power generation and conditioning equipment. Programs have been undertaken to reduce the weight of rotating machines, transformers, switches, inverters, and capacitors. The advances made in these areas are described, and some aspects of the use of these components in the design of lightweight systems are discussed.     

Review on ultra-lightweight flapping-wing nano air vehicles:Artificial muscles,flight control mechanism,and biomimetic wings

Flying insects are capable of flapping their wings to provide the required power and control forces for flight. A coordinated organizational system including muscles, wings, and control architecture plays a significant role, which provides the sources of inspiration for designing flapping-wing vehicles. In recent years, due to the development of micro-and meso-scale manufacturing technologies, advances in components technologies have directly led to a progress of smaller Flapping-Wing Nano Air V...     

Two-dimensional adaptive array for spatially separating andtracking uncorrelated sources

A new structure for the separation and tracking of uncorrelated sources through the use of a 2-dimensional adaptive array is proposed and investigated. The structure consists of a matrix preprocessing beamformer designed to result in outputs which are due to individual sources in the steady state. The preprocessing weights of the beamformer are calculated using the estimated locations of the sources and are updated periodically. Continuous estimation of the source locations is accomplished by using the beamformer outputs to adaptively eliminate correlated components in a reference element of the array while the structure proposed may have rather erratic initial convergence behavior, it has the advantages of being simple to be implemented, fast in tracking, and well suited for applications in mobile communication systems for increasing system capacity     

Monopulse-radar angle tracking in noise or noise jamming

In many monopulse radars, feedback in the angle-tracking servo system is taken to be directly proportional to the monopulse ratio. In those radars, monopulse measurements are conditioned on simultaneous occurrences of receiver sum-channel video exceeding a detection threshold: if a detection fails to occur, the measurement is ignored, and the angle-tracking servo is made to coast. Such conditioning is shown to be necessary in order that the noise power be finite in the servo feedback. The conditional mean value and conditional variance of the monopulse ratio are derived and quantified in terms of threshold level as well as signal-to-noise ratio. The formulation permits the noise covariance between receiver difference and sum channels to be complex rather than only real-valued, so that the sources of noise jamming are not required to be positioned in the receiving-antenna mainlobe and to be copolarized with the antenna response there. Nonfluctuating and Rayleigh-fluctuating target cases are considered and compared, and fluctuation loss is quantified     

Technology games/battlefield 2000

The pervasive impact of power generation on electronic battlefield technologies and the critical need for compact, highly efficient power sources are discussed. Areas that require new and innovative solutions are prime power, batteries, capacitors, switches, and pulser integration. It is concluded that orders of magnitude improvements are needed; technical barriers exist that require invention; power technology needs to be given a high priority in the tech base strategy; and resources must be rejuvenated and expanded to accomplish the required objectives     

飞机电排斥除冰器件设计与仿真

结冰是飞机飞行中的重大安全隐患.电排斥除冰器利用电磁排斥力除去冻结在飞机表面的积冰,具有低功耗、高效率、对飞机气动性能影响小、安装简易等优点.本文采用ANSYS仿真软件,利用磁矢量位有限元仿真方法,构建了飞机电排斥除冰器单组排斥元件有限元模型,通过对模型进行电磁一结构瞬态耦合,分析了单组元件尺寸及通入电流峰值对元件运动...     

Remaining useful life prediction of aircraft lithium-ion batteries based on F-distribution particle filter and kernel smoothing algorithm

As an emergency and auxiliary power source for aircraft, lithium (Li)-ion batteries are important components of aerospace power systems. The Remaining Useful Life (RUL) prediction of Li-ion batteries is a key technology to ensure the reliable operation of aviation power systems. Particle Filter (PF) is an effective method to predict the RUL of Li-ion batteries because of its uncertainty representation and management ability. However, there are problems that particle weights cannot be updated in the prediction stage and particles degradation. To settle these issues, an innovative technique of F-distribution PF and Kernel Smoothing (FPFKS) algorithm is proposed. In the prediction stage, the weights of the particles are dynamically updated by the F kernel instead of being fixed all the time. Meanwhile, a first-order independent Markov capacity degradation model is established. Moreover, the kernel smoothing algorithm is integrated into PF, so that the variance of the parameters of capacity degradation model keeps invariant. Experiments based on NASA battery data sets show that FPFKS can be excellently applied to RUL prediction of Li-ion batteries.     

Integration of Large Power Systems into Manned Space Stations

Essential design factors and system characteristics are explored for integration of large power systems into manned space stations. The impact of the type of power system selected upon the space station is outlined, as is the impact of the mission requirements upon the selection of power systems. Criteria for resolving the selection/application/ integration problems are provided. Comparisons between systems are based on recently defined space-station models for 90-day to five-year mission durations in the 1970' s, with four-to nine-man crews. Power systems encompass power levels from 3 to 50 kWe and include solar cell/battery. fuel cell, hybrid fuel cell/solar cell, radioisotope, and nuclear reactor systems. Thermoelectric, Brayton cycle, organic Rankine, and liquid-metal Rankine power conversion systems are considered for the nuclear energy sources. Both rigid and roll-out photovoltaic array configurations are analyzed with respect to the solar energy source.     

Simulation of DC spacecraft power systems

A modular state-variable approach is presented for DC spacecraft power system modeling and simulation. Each modular component is treated as a multiport network, and a state model is written with the port voltages as the inputs. The state model of a component is solved independently of the other components, using its state transition matrix. The state variables of each component are updated, assuming that the inputs are constant. Network analysis principles are then utilized to calculate the component inputs     

F100/F110发动机与F-15/F-16战斗机使用故障的统计与分析

为借鉴国外航空发动机在设计、研制和使用中积累的经验与教训,通过大量的数据统计与分析,描述美国F-15与F-16战斗机及其装配的F100与F110发动机在使用中发生的重大故障,归纳并总结这些故障在不同阶段、不同部件、不同影响因素的分布情况与规律.分析表明:发动机在前10年或工作35000h左右,故障率高,在之后的较成熟期,故障明显减少;无论是否考虑结构完整性,发动机各种故障会出现在整个使用过程中,但按结构完整性大纲研制的发动机的故障率明显低;在部件故障分布方面,发动机叶轮机是最主要的故障源;在影响因子分布方面,设计、维护、保障和使用不当是发动机出现故障的最主要原因.      

Factors Relating to the Application of Radioisotopes to Circulatory Support Systems

Radioisotope power supplies for heart assist devices and total replacements are being developed. In a radioisotopically powered artificial heart, heat from the decay of radioisotopes would be converted to fluid power to operate a blood pump. Radioisotope power sources offer the advantages of being completely implantable and having a relatively long life. Initial efforts have been directed toward developing conceptual designs of radioisotope heat engines, evaluating candidate radioisotopes fuel forms, and studying the radiation doses to be expected from the various fuel forms. Conceptual design studies indicate that a power supply capable of meeting the specifications of a circulatory support system can be developed. The most promising fuel is plutonium-238. Radiation does not appear to be a problem.     

Propagation and System Accuracy Impact of Major Sensor Errors on a Strapdown Aircraft Navigator

A strapdown system is considered as an unaided inertial navigator aboard an aircraft. Presented here are simulation results detailing the propagation of navigation errors (in nautical miles) due to strapdown sensor errors for four trajectories. They indicate the type of performance that can be expected from a strapdown system utilizing good ?off the shelf? gyros and accelerometers, and dramatically illustrate the improvements necessary in these components to obtain navigation performance comparable to that available from a good gimballed inertial system. The total navigation error for each trajectory is broken down to show the contribution from each of the various error sources. This breakdown quickly reveals which are the critical error sources for a given trajectory class, and also points up the relationship that exists between each individual error source, aircraft maneuvers, and the resulting navigation error. Several of the error mechanisms are discussed at length and a set of linearized differential equations which can be used to analyze error propagations is presented. These results should be of particular interest to the system designer who is faced with the problem of specifying the sensor error parameters necessary to meet mission performance requirements. With an analysis similar to the one presented here, but structured around his own expected mission trajectories, the designer should be able to confidently predict system accuracies and intelligently perform tradeoffs on the critical system parameters.